1. Field of Invention
The present invention relates to a liquid crystal display (LCD). More particularly, the present invention relates to a wire-on-array (WOA) liquid crystal display (LCD) in which gamma voltages are transmitted to source driver circuits through high-input impedance components.
2. Description of Related Art
With the progress of the flat panel display (FPD), there is a tendency to shift conventional cathode-ray tube (CRT) displays to liquid crystal displays (LCD) due to smaller volume, less weight, lower radiation and lower power consumption. Nowadays, LCD panels have been commercially used in consumer products, such as personal digital assistant (PDA), mobile phone, camera, laptop and television.
FIG. 1 shows a framework diagram of a conventional flat panel display 100, such as an LCD, which comprises a substrate 102, a pixel array 104, a plurality of gate driver circuits (not shown in FIG. 1) and source driver circuits 106, a system circuit 108 and a plurality of flexible printed circuit (FPC) boards 110. Generally speaking, in the fabrication of the flat panel display 100, the pixel array 104 having a plurality of pixel elements arranged in columns and rows are fabricated on the substrate 102 usually made of glass, in which each of the pixel elements is provided to control the quantity of light emission. Each of the pixel elements within the pixel array 104 is controlled by the corresponding gate driver circuit and the corresponding source driver circuit 106.
The gate driver circuits and the source driver circuits 106 are usually fabricated on peripheral areas of the pixel array 104 for providing gate voltages and source voltages to each of the pixel elements within the pixel array 104, with the gate voltages sequentially enabling a row of pixel elements within the pixel array 104 and with the source voltages driving the enabled pixel elements for light emission. In this case, gamma voltages are transmitted from the system circuit 108 through each of the flexible printed circuit (FPC) circuits 110 to the corresponding source driver circuits 106. Then the source driver circuits 106 can produce source voltages with respect to data signals received from each of the flexible printed circuit (FPC) boards 110, and further with respect to the gamma voltages received from each of the flexible printed circuit (FPC) boards 110.
Generally, the source driver circuits 106 may be fabricated directly on the substrate 102 using a conventional process, such as chip-on-glass (COG) process, and the system circuit 108 may be fabricated on a printed circuit board (PCB) separated from the substrate 102. Each of the flexible printed circuit (FPC) boards 110 respectively connects each of the source driver circuits 106 to the system circuit 108 in order to transmit required signals including power, data signals and gamma voltages from the system circuit 108 to each of the source driver circuits 106.
In this case, since the flat panel display 100 has a plurality of flexible printed circuit (FPC) boards 110, the cost of the flat panel display 100 is relatively high. Therefore, another flat panel display 200 with only one flexible printed circuit (FPC) board 210 is highly desired, which is schematically shown in FIG. 2. It can be seen that, in FIG. 2, the flat panel display 200 comprises a substrate 102, a pixel array 104, a plurality of gate driver circuits (not shown in FIG. 2) and source driver circuits 206, a system circuit 208 and only one flexible printed circuit (FPC) boards 110. In this case, the source driver circuits 206 for the pixel array 104 are connected in series, and the system circuit 208 can provide required signals including power, data signals and gamma voltages to one of the source driver circuits, such as the front-end source driver circuit 206, through the flexible printed circuit (FPC) board 210. The required signals then can be transmitted to other source driver circuits in a predefined order. With this, each of the source driver circuits 206 can produce source voltages with respect to the data signals and the gamma voltages received from the preceding source driver circuit or directly received from the flexible printed circuit (FPC) board 210. The required signals communicated between the flexible printed circuit (FPC) board 210 and the front-end source driver circuit and between any source driver circuit and its following source driver circuit can be transmitted on wires directly formed on the substrate 102. With only one flexible printed circuit (FPC) board 210, the cost of the flat panel display 200 can be significantly reduced and the area required for the system circuit 108 can be also reduced.
Some problems, however, occur in the conventional wire-on-array (WOA) display. One of the problems is the degradation of the gamma voltages due to transmission loss between different source driver circuits. Specifically, the degradation of the gamma voltages is likely to make the output source voltages from each of the source driver circuits 206 corrected on different bases, which may lead to a banding effect of the whole display image. Therefore, a wire-on-array (WOA) display panel to overcome the afore-mentioned problem is highly desired.